High energy rate forming machine



Jan. 13, 1970 B. l. BROWN HIGH ENERGY RATE FORMING MACHINE 8 Sheets$heet 1 Filed Feb. 27, 1967 NQ QQ m3 /NVEA/7'0/ BON/AED I Beam/1v Jan. 13, 1970 B. l. BROWN HIGH ENERGY RATE FORMING MACHINE 8 Sheets-Sheet 2 Filed Feb 27, 1967 NT W W. A j 7 O M a; .W v 1; WI A 0 M M W; N \h 5 4 Y6 f -HUmUW g mw k w Q QM aw QM Q w\ n QM QM QM J w FL QN V W u mvbm QN M Jan. 13, 1970 B. BROWN HIGH ENERGY RATE FORMING MACHINE 8 Sheets-Sheet 5 Filed Feb. 27, 1967 MIVEA/TOE 50/V/ARO 2? BROWN Jan. 13, 1970 B. 1. BROWN 3,488,990

HIGH ENERGY RATE FORMING MACHINE Filed Feb. 27, 1967 8 Sheets-Sheet 4 EON/APO I EEO/40V ,6M (am Jan. 13, 1970 B. 1. BROWN 3,438,990

HIGH ENERGY RATE FORMING MACHINE Filed Feb. 27, 1967 8 Sheets-Sheet 5 lNVENTO/Q BOA/MED I. Beam Iv fl Km A7702A/E7 w 6 Z 4 Z m m y a w 4/ Z F 2 z w r E Q 6 6 Z Z a w A a z w. 6 Z 1 ir. 4 I 0Z0 W. 1 Z O l It w an: I l I z i ln i m i 1 ii 6 5 g 2 5 2 Jan. 13, 1970 B. l. BROWN HIGH ENERGY RATE FORMING MACHINE 8 Sheets-Sheet 6 Filed Feb. 2'7, 1967 M my 83 mm I III M/VEA/TOE BON/AED I. Bean N A 770EME) Jan. 13, 1970 B. l. BROWN HIGH ENERGY RATE FORMING MACHINE 8 Sheets-Sheet '7 Filed Feb. 27, 196'? lA/VEA/TOE BUN/A20 I Bean/Iv Jan. 13, 1970 B. l. BROWN HIGH ENERGY RATE FORMING MACHINE 8 Sheets-Sheet 8 Filed Feb. 27, 1967 l/VVE/VTOE BO/V/AED I. BROWN United States Patent 3,488,990 HIGH ENERGY RATE FORMING MACHINE Boniard I. Brown, 1502 W. Service Ave., West Covina, Calif. 91790 Filed Feb. 27, 1967, Ser. No. 618,876

Int. Cl. B21d 7/06; BZlj 9/18, 7/36 US. Cl. 72-407 16 Claims ABSTRACT OF THE DISCLOSURE An impact or high energy rate forming machine having a pair of opposing rams adapted to be impelled toward each other, and having mechanical linkage, preferably a toggle linkage, for synchronized ram action.

This invention relates generally to machines for impact forming metals and other work materials; more particularly, the present invention relates to improvements in impact forming machines of the kind which are characterized by a pair of opposing forming rams adapted to be driven toward one another to impact form a workpiece therebetween.

As will app-ear from the ensuing description, the improved impact forming machine of the invention may be employed for a variety of impact forming applications. In this regard, it should be noted at the outset that the expression impact forming, as it is used herein, is intended to encompass any and all impact forming operations which involve percussive contact of opposing, coacting forming elements with an intervening workpiece to mold, shear, deform, punch, or otherwise work or form the workpiece. However, the present forming machine is intended primarily for so-called high energy rate forming applications. For this reason, the invention will be described in connection with such high energy rate forming applications.

Generally speaking, high energy rate forming of a workpiece involves placement of the workpiece within the cavity of a forming die and subsequent high velocity impulsion of the die and a forming ram toward one another to bring the ram and the workpiece into per cussive contact of such extremely high kinetic energy and short time duration that the material of the workpiece undergoes plastic deformation into conformance with the die cavity. In some high energy rate forming machines, the forming die is effectively stationary and the forming ram is driven toward the die to effect the high energy rate forming action, just explained. High energy rate forming machines of this type, however, particularly those adapted for repetitive cycling operation, are characterized by certain disadvantages. Thus, primarily because of the high energy rates, stresses, and ram velocities involved in high energy rate forming, problems of unreliability, maintenance, and short service life have been general. These problems have been particularly serious With respect to impact loading. and inability to isolate static machine components from such loading and high rate stresses. Generally speaking, efforts to relieve these problems have involved relatively complex and specialized machine structures and mechanisms which are relatively massive as well as difficult and costly to fabricate.

3,488,990 Patented Jan. 13, 1970 Moreover, the ram of these forming machines tends to rebound after its initial forming impact with the workpiece in such a Way that the workpiece is subjected to several succesive blows by the ram. Such repeated impact of the ram against the formed workpiece results in damage to the workpiece and produces additional stresses in the machine. Another disadvantage of the high energy rate forming machines of the kind under discussion is their relatively low efliciency. This low efficiency is due, in large part, to the energy losses which typically occur during operation of these machines. A further disadvantage of the existing forming machines resides in the inaccessibility and difiiculty of servicing, replacing, or repairing machine components, particularly the annular sealing elements which are utilized in the pressure chambers of many forming machines.

Improved high energy rate forming machines have been devised which avoid the above noted and other disadvantages of the single ram forming machines. These improved forming machines are characterized by a pair of opposing forming rams which are impelled toward one another to etfect high energy rate forming of a'workpiece situated between the rams. Such dual ram high energy rate forming machines are so constructed and operated that the forming rams possess approximately the same kinetic energy at impact. Accordingly, substantially all ofthe kinetic energy of the rams is absorbed by the rams themselves and the intervening workpiece, and the rams are arrested at the conclusion of their forming strokes without any appreciable stressing or shock loading of the machine frame or the other machine components. Such dual ram high energy rate forming machines, therefore, are characterized by improved reliability, longer service life, greater simplicity of construction, lower cost of manufacture, immunity to breakdown, ease of repair, replacement, and servicing the machine components, when necessary, superior product formation, and other highly desirable operating characteristics.

It is obvious at this point that optimum operation of a dual ram high energy rate forming machine requires precise matching of the kinetic energies of the forming rams at impact. The kinetic energy of each forming ram, of course, is a combined function of its mass and velocity. Some existing forming machines of this kind utilize forming rams of substantially equal mass. In this case, matching of the ram energies requires precise equalizing of the ram velocities at impact. Other high rate energy forming machines of the kind under discussion employ forming rams, or the like, of different mass. Matching of the kinetic energies of the rams in these latter machines requires precise differential ram velocities at impact. Precise control of the ram velocities at impact, then, is essential to optimum operation of both types of dual ram high energy rate forming machines.

One of the outstanding deficiencies of the existing dual ram forming machines resides in the fact that such precise control of the ram velocities at impact is difficult or impossible to achieve. This is due to the fact that the existing machines are devoid of any means to positively synchronize release of the rams and subsequent movement of the rams through their forming strokes. Thus, a typical high energy rate forming machine of the kind under discussion includes means which cooperate with the forming rams to define expansible pressure chambers containing a working fluid, such as nitrogen and means for compressing the working fluid to a high pressure when the rams are retracted. This working fluid is effective, upon release of the rams, to impell the rams toward one another at high velocity, thus to accomplish the high energy rate forming action, discussed earlier. Owing to the fact that the forming rams are capable of independent movement, to the high velocities to which the rams are accelerated, and to the extremely short time duration of the working strokes of the rams, the various parameters which affect or govern the ram velocities at impact are extremely critical. For example, since the rams are accelerated from rest, the ram velocities at impact are functions of the time duration or length of the working strokes of the rams. Accordingly, even though the rams are impelled at the correct rates of acceleration to achieve precise matching of the ram energies at impact, actual energy matching will occur only if release of the rams is precisely synchronized, such that the working strokes of the rams are of precisely the correct time duration and length and impact occurs at a precisely predetemined position along the direction line of ram travel. Thus, a delay, even on the border of a few microseconds, in the release of one ram will result in a reduced working stroke and impact velocity of the delayed ram and a correspondingly increased working stroke and impact velocity of the other ram. Under these conditions, the kinetic energy of the delayed ram at impact will be less, and the energy of the other ram will be greater, than that required for precise matching of the ram energies at impact. Accordingly, the machine frame and its supporting floor may be subjected to shock loading and resulting high stresses. Similar undesirable results may obtain if the rams, even though properly released, are subjected to improper working fluid pressure or to retarding forces which prevent normal acceleration of the rams.

It is obvious, of course, that the various parameters which affect the ram velocities at impact in the existing dual ram high energy rate forming machines are extremely critical, as just stated, for the reason that the ram movements are not mechanically or positively synchronized. Accordingly, precise control of these parameters is necessarily relied on to achieve matching of the ram energies. This precise control, however, is extremely diflicult to achieve, particularly in a high energy rate forming machine designed for repetitive cycling, and requires a forming machine which is rather complex in construction, costly to manufacture, difficult to maintain in the proper state of adjustment, and is otherwise not totally satisfactory.

One important aspect of this invention is concerned with an improved impact forming machine, which is particularly designed for high energy rate forming applications, wherein the forming rams are operatively connected by mechanical linkage means in such a way as to effect precisely synchronized release and/or precisely synchronized travel of the rams from their retracted positions to their forming positions. Precise matching of the kinetic energies of the rams at impact is thereby attained with a forming machine of utmost simplicity, minimum cost, maximum reliability, and optimum repetitive cycling capability Some of the existing dual ram high energy rate forming machines of the kind under discussion are subject to another deficiency which this invention also seeks to overcome. The forming machines referred to here are of the type wherein the working fluid is partially or totally pressurized to its high initial working pressure by retraction of the forming rams. These machines comprise power means, such as hydraulic or pneumatic rams, for retracting the forming rams against the pressure of working fluid sealed within the expansible ram driving chambers. The rams are then latched in their retracted positions to condition the machines fer a subsequent high energy rate forming cycle. The existing machines of this kind are not tet y'sa isfact y or -th ea on ha he r m retracting means employed therein are devoid of any mechanical force multiplying or amplifying structure and are thus required to operate at a relatively high pres sure. The existing ram retracting means, therefore, tend to be quite massive, complex in construction, costly to manufacture, and impose undesirable drag or retarding forces on the forming rams. Moreover, many of these existing forming machines require one means for retracting the rams and completely separate means for locking the rams in their retracted positions.

According to another of its important aspects, the present invention provides a high energy rate forming machine equipped with improved means for retracting the rams against the pressure of working fluid in the expansible ram driving chambers, thus to compress the working fluid to the high pressure level required for optimum high energy rate forming operation of the machine. These ram retracting means develop a mechanical advantage which permits the retracting means to be powered by a relatively small power source, such as a low pressure hydraulic or pneumatic actuator, that is relatively compact, economical to manufacture, and imposes minimal drag on the forming rams during their forming strokes. An additional feature of the preferred form of the invention resides in the fact that the mechanical advantage of the retracting means increases as the forming rams approach their retracted positions and, therefore, as the pressure of the working fluid increases. Moreover, the present ram retracting means may serve the multiple function of retracting the rams against working fluid pressure, retaining the rams in their retracted positions in readiness for a subsequent high energy rate forming cycle of the machine, and simultaneously releasing the rams for movement through their forming strokes.

A further important aspect of the invention is concerned with a high energy rate forming machine wherein the several improved machine functions heretofore stated are accomplished by a unique toggle which is operatively connected between the forming rams. This toggle is effective, when driven to its dead center position, to simultaneously retract the forming rams against working fluid pressure with a mechanical advantage which increases as the rams approach their retracted positions. The toggle, when released for movement from its dead center position, is effective to constrain the rams for precisely synchronized movement to their forming positions. Precise matching of the kinetic energies of the rams at impact is thereby achieved, whereby shock loading of the machine frame and its supporting floor is virtually eliminated. The complexity and cost of the forming machine is also greatly reduced. Moreover, the toggle connection between the forming rams uniquely adapts the present forming machine to relatively high rate repetitive cycling suitable for production line operation. As will appear from the ensuing description, one disclosed embodiment of the invention is particularly adapted to such high rate repetitive cycling operation.

A further advantage of the forming ram retraction and synchronizing means embodied in the present invention resides in the fact that not only may the kinetic energies of the rams atimpact be precisely matched or balanced, as noted earlier, but further, these ram energies may be regulated to provide a work forming impact of any desired intensity. This feature of the machine adapts the latter to high energy rate forming of a great variety of work materials and shapes andenables the machine to form finished work products which are superior to those produced by the existing high energy rate forming machines.

A particularly important advantage of the present forming machine is its superiority to the existing forming machines from the standpoint of safety. Thus, in the existing dual ram forming machines, the forming rams are capable of independent movement, as already noted, As a conseq en it i po sible that one ram may jam in a stationary position along its forming stroke, while the remaining ram continues its high velocity forming movement. Under these conditions, the ram energies at impact are not matched and the machine may suffer severe damage. More serious, however, particularly in high energy rate forming applications, is the fact that high velocity unbalanced impact of a moving ram against the stationary ram may cause disintegration of the forming machine and thus create an extremely serious safety hazard. The present improved forming machine construction avoids these hazards of the existing forming machines. Thus, since the forming ram movements are positively synchronized in the present machine, jamming of one ram will either arrest the other ram, or the moving ram will free the jammed ram. In either case, impact of the forming rams without matching or balancing of the ram energies, and hence the hazards attendant to unbalanced ram impact, are avoided.

It is a general object of the invention, therefore, to provide an improved dual ram impact forming machine which is particularly suited for high energy rate forming applications.

A more specific object of the invention is to provide an improved impact forming machine of the character described wherein the forming rams are interconnected by mechanical linkage means which eflect precisely synchronized release of the rams from their retracted positions and/or precisely synchronized travel of the rams through their forming or working strokes, in such manner as to achieve precise matching or balancing of the kinetic energies of the rams at impact, thereby to minimize or eliminate impact loading and the attendant high stresses on the machine frame and its supporting floor, eliminate the safety hazards associated with high energy rate forming machines having independently movable rams, prolong the service life of the machine, minimize the possibility of machine failure, improve the operating reliability of the machine, permit regulation of the ram energies at impact, and enhance the quality of the work product produced by the machine.

Another object of the invention is to provide a high energy rate forming machine wherein retraction of the forming rams is utilized to compress a working fluid to a high pressure level for subsequently impelling the rams through their forming strokes and wherein further the machine is equipped with novel force multiplying means for retracting the rams against working fluid pressure, thus to permit actuation of the ram retracting means with a power source of minimum size.

A related object of the invention is to provide a forming machine according to the foregoing object wherein the mechanical advantage of the ram retracting means increases as the rams approach their fully retracted positions, whereby the effective retracting force on the rams increases as the opposing force of the compressed working fluid increases.

Yet another object of the invention is to provide an improved impact forming machine of the character described wherein the ram releasing, synchronizing, retracting, and force multiplying functions of the -machine are performed by a unique toggle connection between the forming rams.

A further object of the invention is to provide an improved impact forming machine of the character described which is uniquely adapted to repetitive cycling operation.

A still further object of the invention is to provide an improved impact forming machine of the character described wherein the forming ram structure of the machine is rotatable to a horizontal attitude, thus to neutralize the affect of gravity on the ram structure.

Yet a further object of the invention is to provide an improved impact forming machine of the character described which is relatively simple in construction, light weight, compact, economical to manufacture, reliable in operation, safe to use, and is otherwise ideally suited to its intended purposes.

Other objects, features and advantages of the present invention will become apparent to those versed in the art from a consideration of the following description, the appended claims and the accompanying drawings, where- FIGURE 1 is a perspective view, partially broken away, of an improved impact forming machine according to the invention;

FIGURE 2 is a side elevation of the machine with parts broken away for the sake of clarity;

FIGURE 2a is a view similar to FIGURE 2, on reduced scale, illustrating the machine parts in one operative position;

FIGURE 2b is a view similar to FIGURE 2a illustrating the machine parts in another operative position;

FIGURE 3 is a section taken on line 33 of FIGURE 2 illustrating the forming rams of the machine in their extended forming positions;

FIGURE 3a is an enlarged section taken on line 3a-3a in FIGURE 3 and illustrating a wrist pin cushioning means embodied in the forming machine;

FIGURE 3b is a section similar to FIGURE 3a illustrating a modified wrist pin cushioning means;

FIGURE 4 is a section similar to FIGURE 3, on reduced scale, illustrating the forming rams in their retracted positions;

FIGURE 5 is a perspective view of a bearing fork which is utilized in the machine;

FIGURE 6 is a side elevation of the machine, on reduced scale, illustrating the ram structure of the machine rotated through from its position of FIGURE 1;

FIGURE 7 diagrammatically illustrates the hydraulic circuitry of the machine;

FIGURE 8 is a perspective view, partially broken away, of a modified impact forming machine according to the invention;

FIGURE 9 is a reduced front elevation of the modified forming machine;

FIGURE 10 is a reduced side elevation of the modified forming machine;

FIGURE 11 is an enlarged section taken on line 11-11 in FIGURE 9;

FIGURE 12 is an enlarged section taken on line 1212 in FIGURE 11;

FIGURE 13 is an enlarged section taken on line 1313 in FIGURE 11;

FIGURE 14 is a section taken on line 14--14 in FIG- URE 12;

FIGURE 15 is a perspective detail of a toggle knee joint embodied in the modified forming machine;

FIGURE 16 is a fragmentary view illustrating certain parts of the machine, shown in FIGURE 12, in other operative positions; and

FIGURE 17 diagrammatically illustrates the hydraulic circuitry of the modified forming machine.

Referring to the drawings in general terms, impact forming machine 10 which has been selected for illustration in FIGURES 1 through 7 of these drawings comprises a frame 12 mounting a pair of forming rams 14 for movement relative to the frame along a common direction line 16. Rams 14 are movable between remote retracted positions, shown in FIGURE 4, and proximate forming positions, shown in FIGURE 3. Associated with the forming rams 14 are retracting means 18 for driving the rams from their forming positions to their retracted positions, and driving or impulsion means 20 for driving or impelling the rams from their retracted positions to their forming positions. In the particular forming machine illustrated, the ram impulsion means 20 comprise a working fluid, which is compressed to a high pressure level by retraction of the rams and subsequently impells the rams to their forming positions. The strokes of the forming rams 14 which involve movement of the rams from their retracted positions to their forming positions are referred to herein as their forming or working strokes.

The ram retraction means 18 comprise power means 22 for producing a ram retraction force and linkage means 24 for mechanically amplifying the retraction force and transmitting the amplified force to the forming rams 14 in directions to retract the rams. In the illustrated forming machine, the linkage means 24 serve the additional functions of retaining the forming rams 14 in the retracted positions against the thrust of the ram driving or expulsion means 20 to condition the machine for subsequent forming strokes of the rams, synchronizing release of the rams from their retracted positions to initiate these forming strokes, and synchronizing movement of the rams through their forming strokes to equalize the ram impact velocities. The forming rams 14 are matched so as to have equal mass. Accordingly, when the rams are impelled through their forming strokes by the ram impulsion means 20, the rams arrive at their forming positions of FIGURE 3 with equal kinetic energy.

The forming rams 14 have confronting working ends 14a mounting die holders 26. Releaseably secured in these die holders are work forming dies 28. These work forming dies have mating die cavity shapes (not shown) which define a die cavity having the desired shape of the finished work product when the forming dies are placed in contact.

Briefly, a typical impact forming cycle of the illustrated impact forming machine involves initial activation of the ram retracting means 18 to drive the forming rams 14 to their retracted positions of FIGURE 4. At some point in this retraction stroke of the forming rams, a workpiece 30 is placed within the cavity of one of the forming dies 28. As noted earlier, retraction of the forming rams 14 occurs against the thrust of the ram driving or impulsion means 20 and conditions these means for subsequently impelling the rams to their forming positions. An important feature of the invention resides in the fact that mechanical advantage of the ram retracting and synchronizing linkage means 24 permits the use of relatively small compact power means 22 for retracting the rams, thus minimizing the complexity, cost, and overall size and weight of the machine. Moreover, as will appear from the ensuing description, the linkage means 24 are uniquely constructed and arranged to permit both maximum utilization of the impact energy of the forming rams 14 and regulation of this impact energy, thus to adapt the machine for impact forming a wide variety of work materials and shapes.

After the forming rams 14 have been fully retracted, they are released for impulsion through their forming or working strokes by the thrust of the ram driving or impulsion means 22. As the rams approach the ends of these forming strokes, the forming dies 28 on the working ends 14a of the forming rams 14 enter into percussive work forming relation in such a way that the workpiece 30 is deformed into conforming relation with the die cavity defined by the forming dies. The illustrated forming machine is a high energy rate forming machine wherein the forming rams 14 are driven through their forming strokes at sufiiciently high velocity to cause high energy rate forming of the workpiece 30. As noted earlier, during such high energy rate forming of a workpiece, the material of the workpiece undergoes plastic flow into conformance with the die cavity. As is well known in the art, such high energy rate forming may be utilized to form to a desired finished shape, with great precision, a variety of relatively hard work materials, including both metallic and non-metallic materials, which are extremely difificult or impossible to form in any other way.

A highly important feature of the illustrated forming machine 10 resides in the equal masses of the forming rams 14 and the accurately synchronized movement of the rarns through their forming strokes to achieve equal impact velocities of the rams, as noted earlier. Thus, this precise ma chi g of the ram masses and velocities effects precise matching of the kinetic energies of the rams at impact. As a consequence, the machine frame and its supporting floor are not subjected to any appreciable shock loading so that it is unnecessary to provide the machine with the usual rugged foundation required by many high energy rate impact forming machines. The precise matching or balancing of the kinetic impact energies of the forming rams 14 which is achieved in the present forming machine by virtue of the positively synchronized forming movements of the rams also permits a relatively light weight, low cost machine construction as well as convenient machine installations which have hitherto been impossible, owing to the massive size and weight of the existing machines. In the illustrated forming machine, for example, the forming ram structure is pivotally mounted to enable rotation of the ram structure to any desired angular position or attitude. The forming ram structure may, for instance, be rotated to a horizontal attitude to eliminate the affect of gravity on the rams.

Referring now in greater detail to the illustrated forming machines 10, the machine frame 12 comprises a lower base portion 32 including a bottom mounting plate 34 and spaced parallel plate-like arms 36 rising from the mounting plate. Positioned between the upper ends of the base arms 36 is an upper frame structure 38 including four essentially identical, generally cruciformed shaped frame plates 40. Each frame plate 40 has a first pair of aligned, oppositely directed arms 44 extending at right angles to the arms 42. The several frame plates 40 are oriented with their corresponding arms 42 and 44 aligned in directions normal to the plates, as shown. The power means 22 for retracting the forming rams 14 includes four fluid pressure actuators 46 having cylinders 48 extending lengthwise of and positioned at their inner ends between the outer ends of the arms 42 of the two outer frame plates and the adjacent inner frame plates 48, as shown. The inner ends of these actuator cylinders have external rectangular shoulders 50 which seat flush against the confronting surfaces of and are bolted or otherwise rigidly joined to the adjacent frame plates 46, thus to rigidly join each outer frame plate to its adjacent inner frame plate. The two actuator cylinders 48 between each outer frame plate and the adjacent inner frame plate are coaxially aligned and extend in opposite directions from the plates, as shown.

Each actuator cylinder 48 contains a piston 52 having a rod 54 which extends through the inner end of the respective cylinder. Fixed on the inner end of each piston rod is a bearing fork or clevis 56. The operation of the actuators 46 will be explained presently.

The forming ram drive or impulsion means 20 comprise coaxial ram cylinders 58 which extend lengthwise of and are positioned at their inner ends between the outer ends of the arms 44 of the two inner frame plates 40. The ram cylinders 58 are welded or otherwise rigidly attached to the inner frame plates and thus serve to rigidly join these plates to one another. The inner ends of the ram cylinders 58 open toward one another. The outer end of the ram cylinders are closed by end caps 60. The forming rams 14 comprise cylindrical pistons which slide in the ram cylinders 58, respectively. The forming rams 14 and the ram cylinders 58 cooperatively define expansible pressure chambers 62 containing a working fluid 64, such as gaseous nitrogen. Other possible working fluids are certain liquids, such as Texaco Regal B. In the event that a liquid is employed as a working fluid, neoprene balls filled with nitrogen may be placed in the pressure chambers 62 with the liquid to provide controlled, extended release of the energy contained in the working liquid when compressed. In the outer ends of the ram cylinders 58 are fluid ports 66 through which the working fluid may be introduced into the pressure chambers 62. It is significant to note at this point that retraction of the forming rams 14 in the 9 ram cylinders 58 is effective to reduce the volume of the expansible pressure chamber 62 and thereby compress the working fluid 64 in the chambers. In most high energy rate forming applications, the working fluid 64 is introduced into the pressure chamber 62 under initial pressure such that the Working fluid is elevated to a working pressure on the order of 2,000 psi. by retraction of the forming rams 14.

It is evident at this point that the actuator and ram cylinders 48, 58 rigidly join the frame plates 40 to form the integral upper frame structure 38. Rigidly joined to the outer sides of the two outer frame plates 40, at the centers of these latter plates, are cylindrical bosses 68 from which extend coaxial journals or trunnions 70. These trunnions are rotatably supported in the upper ends of the upstanding frame base arms 36 and serve to pivotally mount the upper frame structure 38 on the frame base 32 for turning on the horizontal axis of the trunnions.

The illustrated ram retracting and synchronizing linkage means 24 comprise a pair of toggles 72 located at opposite sides of the ram cylinders 58, within the spaces between the two outer frame plates 40 and the adjacent inner frame plates. Each toggle has a pair of toggle bars 74, 76, the adjacent ends of which are pivotally joined by a knee joint 78 including a knee shaft 80. The ends of the toggle knee shafts 80 project beyond their respective toggle bars 74, 76 into aligned guide tracks or slots 82 in the adjacent frame plates 40. These guide slots are disposed in a common plane containing the axes of the ram actuator cylinders 48. The outer ends of the toggle bars 74, 76 are pivotally attached to the forming rams 14. To this end, the rams are provided with transverse wrist pins 84 which extend through axial guide slots 86 in the ram cylinders 58 and aligned guide slots 88 in the frame plates 40. The ram cylinder slots 86 and the frame plate slots 88 are disposed in a common plane normal to the longitudinal axes of the actuator cylinders 48 and containing the common axis of the ram cylinders 58. The outer ends of the toggle bars 74, 76 are rotatably secured to the wrist pins 84 in the regions between the outer and adjacent inner frame plates 40.

It is now evident that the toggles 72 interconnect the forming rams 14 in such a way as to constrain these rams to precisely synchronized movement between their retracted positions of FIGURE 4 and their forming positions of FIGURE 3. As the rams travel back and forth between these positions, the toggle knee shafts 80 and wrist pins 84 slide back and forth along their respective frame plate guide slots. It is significant to note here that the toggle knee joints 78 are movable between the extreme or limiting positions illustrated in FIGURES 2 and 2b and through the intervening dead center position illustrated in FIGURE 2a. In this dead center position, the knee joints are located in a plane containing the toggle wrist pins 84. Movement of the toggle knee joints 78 from either limiting position to the dead center position is obviously effective to drive the formng rams 14 from their forming positions to their retracted positions with a mechanical advantage which increases sharply as the rams approach their retracted positions. Movement of the forming rams from their retracted positions to their forming positions with the toggle knee joints initially slightly offset from their dead center positions, in turn, is effective to drive these knee joints to their adjacent limiting positions.

It will be recalled that the piston rods 54 of the ram actuators 46 mount bearing forks 56. These bearing forks have spaced fork arms 90 formed with outwardly opening, generally semi-circular bearing recesses 92 and are adapted to rotatably seat against the adjacent toggle knee joints 78 in straddling relation to the toggle bars 76. The toggle bars 74 are longitudinally slotted to straddle the bearing forks 56. Suitable keying means (not shown) are provided within the actuator cylinders 48 for re- 10 taining the bearing forks 56 in the proper attitude for seating against the toggle knee joints 78, in the manner best illustrated in FIGURE 2.

As noted earlier and hereinafter explained in greater detail, the forming rams 14 are driven or impelled at high velocity from their retracted positions to their forming positions to effect impact forming of the workpiece 30 within the cavity defined by the forming dies 28. This impact forming action abruptly arrests the forming rams 14 at the conclusion of their high velocity forming strokes. It is obvious, of course, that during these high velocity forming strokes, the toggle wrist pins 84 and the toggle bars 74, 76 connected to the wrist pins acquire substantial kinetic energy. Accordingly, the wrist pins are subjected to severe deceleration forces upon arresting of the forming rams after impact. If the wrist pins were rigidly secured to the forming rams, as by press fitting the pins into the rams, for example, the forces active on the pins at impact might bend the outer extending ends of the pins or Brinell the pins into their bearing seats within the forming rams. For this reason, the forming rams 14 are preferably equipped with shock absorbing means for arresting the wrist pins without excessive shock at the conclusion of the ram forming strokes.

FIGURE 3a illustrates one possible shock absorbing means for this purpose. In this figure, the wrist pin 84 extends through a transverse opening 94 in the forming ram 14, which opening is slightly elongated in the axial direction of the ram. Extending axially through the ram and communicating at one end with the wrist pin opening 94 is a bore 96 containing an orifice plate 98. Orifice plate 98 defines a pair of chambers 100 and 102 located at opposite sides, respectively, of the orifice plate. These chambers communicate through a central orifice 104 in the plate 98. The open end of chamber 102 is closed by a sealing disc 106 which is bolted to the end of the forming ram 14, as shown. The ram chambers 100 and 102 contain pistons 108 and 110, respectively. Formed in one end of the piston 108 is a cylindrically curved recess 112 for receiving the wrist pin 84. Extending axially from the opposite end of the piston 108 is a tapered metering pin 114. Piston has a generally flat disc shape. Filling the chamber space between the pistons 108 and 110 is a liquid 116. The chamber space defined between the sealing disc 106 and the piston 110 is filled with a gas 118 under high pressure.

The pressure of the gas 118 reacts on the piston 108 through the intervening piston 110 and liquid 116 and normally serves to firmly retain the wrist pin 84 in seating engagement with the adjacent wall of the wrist pin opening 94. It is significant to note here that this wall provides a rigid seat against which the wrist pin is urged by the force transmitted to the wrist pin by the respective toggle 72 during retraction of the ram 14. During the major portion of each forming stroke of the ram, the wrist pin remains in contact with this rigid seat on the ram. When the forming ram 14 reaches the end of its forming stroke it is abruptly arrested by the work forming impact, as explained earlier. The force exerted on the wrist pin 84, by virtue of the momentum acquired by the pin and the toggle bars 74 during the forming stroke of the ram, tends to drive the wrist pin, and hence the ram piston 108, forwardly in the ram chamber 100. Forward movement of the piston 108 expels the liquid 116 through the orifice 104, thereby driving the piston 110 forwardly against the gas pressure in the ram chamber 102, and results in entry of the piston metering pin 114 into the orifice to progressively throttle liquid flow through the orfice. The wrist pin 84 is thereby gradually arrested without damage. FIGURE 3b illustrates a modified wrist pin shock absorbing means 120 wherein the fluid damping means of FIGURE 3a are replaced by a compression spring 122. It will be understood that wrist pin shock absorbing means are embodied in both forming rams 14.

Reference is now made to FIGURE 7 which illustrates the hydraulic circuitry of the forming machine described above. It will be readily observed in this figure that one pair of the ram actuators 46 is located at one side of a plane normal to the axes of the actuator cylinders 48- and containing the common axis of the ram cylinders 58 and the remaining pair of actuators is located at the opposite side of this plane. For convenience in the ensuing description, these actuator pairs are identified by the reference numerals 46a and 4612, respectively. The hydraulic circuit of the forming machine includes a hydraulic pump 124 which receives hydraulic fluid from a reservoir 126 and discharges the fluid under pressure to the inlet 128a of a four-way solenoid valve 128 having three outlets 128b, 1280 and 128d. Valve outlet 128b is connected to the reservoir 126 through a return line 130. Valve outlet 1280 is connected to the inner ends of the cylinders 48 of the ram actuators 46a through a hydraulic line 132 and to the outer ends of the cylinders of the ram actuators 46b through a hydraulic line 134. Arranged in parallel in the hydraulic line 134 are an orifice 136 and a check valve 138. Similarly, valve outlet 128d is connected to the inner ends of the cylinders 48- of the ram actuators 46b through a hydraulic line 140 and to the outer ends of the cylinders of the ram actuators 46a through a hydraulic line 142. Arranged in parallel in the hydraulic line 142 are an orifice 144 and a check valve 146. Leading from the solenoid valve 128 are electrical leads 148 through which the valve may be energized for selective operation thereof to either of two positions. In one of these positions, the valve communicates the valve inlet 128a to the valve outlet 1280 and the valve outlet 128b to the return line 130. In this valve position, then, the hydraulic circuit is conditioned for high pressure fluid flow from the valve 128 to the inner ends of the ram actuators 46a and the outer ends of the ram actuators 46b and for return flow of the hydraulic fluid from the outer ends of the ram actuators 46a and the inner ends of the ram actuators 46b to the reservoir 126. In its second position, the valve 128 communicates the valve inlet 128a to the valve outlet 128d and the valve outlet 1280 to the return line 130. In this valve position, the hydraulic circuit is conditioned for high pressure fluid flow from the valve to the inner ends of the ram actuators 46b and the outer ends of the ram actuators 46a and for return flow of hydraulic fluid from the inner ends of the ram actuators 46a and the outer ends of the ram actuators 46b to the reservoir 126. It is evident at this point, therefore, that operation of the valve 128 to its first above described position, with the hydraulic pump 124 operating, effects simultaneous right hand extension of the piston rods 54 of the ram actuators 46b and right hand retraction of the piston rods of the ram actuators 46a, as the actuators are viewed in FIGURE 7. Operation of the valve 128 to its second position effects simultaneous left hand extension of the piston rods of the ram actuators 46a and left hand retraction of the piston rods of the ram actuators 4612. Each orifice 136 and 144 restricts hydraulic fluid flow to the outer ends of the actuators in such a way as to limit the rate of extension of the actuator piston rods. The check valves 138, 146 open to permit unrestricted hydraulic fluid flow from the outer ends of the actuators, through the valve 128, to the reservoir 126, thus to permit rapid retraction of the actuator piston rods. In this regard, the hydraulic lines communicating the outer ends of the actuators to the reservoir preferably have a relatively large bore in order to accommodate unrestricted hydraulic fluid flow from the actuators to the reservoir.

Extending between the ports 66 in the outer ends of the ram cylinders 58 is a fluid conduit 150 which communicates the expansible pressure chambers 62 defined by these cylinders. Conduit 150 is also connected, through a valve 152, to a source 154 of the working fluid 64 contained in the ram cylinders. The fluid conduit 150 has a relatively large bore and serves to constantly equalize the working fluid pressure in the expansible pressure chambers of the ram cylinders. This equalization of the working fluid pressure is highly desirable, for reasons which will appear presently.

A typical forming cycle of the forming machine 10 will now be described. In the normal condition of the machine, the forming rarns 14 are retained in their extended forming positions of FIGURE 3 by the working fluid pressure in the expansible pressure chambers 62 and the knee joints 78 of the toggles 72 occupy one of their limiting positions. In the following discussion, it is assumed that the knee joints initially occupy the limiting positions illustrated in FIGURE 2. In this normal condition of the machine, the piston rods 54 of the ram actuators 46a are fully retracted and the piston rods of the ram actuators 46b are fully extended, as shown in FIG- URE 2.

With the forming machine in this initial condition, a forming cycle of the machine is initiated by operating the valve 128 to communicate the valve inlet 128a to the valve outlet 128d and the valve outlet 128c to the return line 130. In this valve position, the ram actuators 46a are pressurized to extend their respective piston rods 54 and the ram actuators 46b are pressurized to retract their respective piston rods. Extension of the piston rods of the ram actuators 46a drives the bearing forks 56 on these rods inwardly against the toggle knee joints 78, thereby driving these joints inwardly toward their dead center positions of FIGURE 2a. This inward movement of the toggle knee joints causes the toggles 72 to exert outward forces on the forming rams 14 which retract these rams against the pressure of the working fluid within the expansible pressure chambers 62. Outward retraction of the rams reduces the volume of the pressure chambers and thereby compresses the working fluid in the chambers. It is significant to note here that the toggles 72 produce a force multiplying action which amplifies the ram retraction force generated by the ram actuators 46a, thus permitting compression of the working fluid 64 within the expansible pressure chambers 62 to a high pressure level by retraction of the rams with relatively small low pressure ram actuators. It is further significant to note that the mechanical advantage of the toggles 72 increases sharply as the toggle knee joints 78 approach their dead center positions and the forming rams 14 approach their fully retracted positions. Accordingly, the mechanical advantage of the toggles enhances the retraction force amplification produced by these toggles and increases with the increase in working fluid pressure occasioned by approach of the forming rams 14 to their fully retracted positions. As a consequence, the pressure of the hydraulic fluid delivered to the ram actuators 46a may remain relatively constant, at a relatively low pressure level, throughout the full stroke of these actuators. At some point during this retraction stroke of the forrning rams 14, a workpiece 30 is placed in the cavity of the lower forming die 28.

Arrival of the forming rams 14 in their fully retracted positions of FIGURE 4 occurs simultaneously with movement of the toggle knee joints 78 to their dead center positions of FIGURE 2a. At this point, the forming machine 10 is conditioned for impulsion of the forming rams 14 through their forming strokes under the force of the compressed working fluid 64 in the expansible pressure chamber 62. These forming srtokes of the rams are initiated by continued driving of the toggle knee joints 78 through their dead center positions to slightly over center positions. Movement of the knee joints to these over center positions simultaneously releases the forming rams for high velocity impulsion through their forming strokes by the compressed working fluid and results in snapping of the toggle knee joints to their left hand limiting positions of FIGURE 2!). In this regard, it will be recalled that check valves 138, 146 embodied in the hydraulic circuit of the forming machine open to 13 accommodate rapid retraction of the actuator piston rods. Accordingly, the piston rods of the ram actuators 46b are fully retracted when the forming rams 14 are thus released for movement through their forming strokes, whereby the latter actuators do not impede forming movement of the rams.

Arrival of the forming rams 14 at their extended forming positions of FIGURE 3 brings the forming dies 28 into percussive forming relation about the workpiece 30 currently positioned in the lower die. The workpiece is thereby subjected to a high intensity impact which deforms the material of the workpiece into conforming relation with the die cavity defined by the mating forming dies 28. This completes one forming cycle of the forming machine. The next forming cycle of the machine is initiated by operating the valve 128 to extend the piston rods 54 of the ram actuators 46b and retract the piston rods of the ram actuators 46a. During this latter forming cycle, the toggle knee joints 78 are driven to the right from their limiting position of FIGURE 211, through their dead center position of FIGURE 2a, to their limiting position of FIGURE '2, thus to initially retract the forming rams 14 against the working fluid pressure in the expensible pressure chamber 62 and compress this working fluid and thereafter release the forming rams for impulsion through their forming strokes under the force of the compressed working fluid in essentially the same way as described earlier in connection with the first forming cycle of the machine. At some point during the retraction strokes of the forming rams 14, the previously formed workpiece is removed from its containing forming die 28 and a new workpiece is placed in the lower forming die. The following working or forming strokes of the forming rams 14 brings the forming dies 28 into percussive forming relation about this new workpiece, thereby deforming the latter into conforming relation with the die cavity, as before. A third forming cycle of the machine may then be effected by again driving the toggle knee joints 78 to the left from their limiting position of FIG- URE 2 to their limiting position of FIGURE 2b.

In the foregoing discussion, it has been assumed that the upper frame structure 38 of the forming machine is oriented in the position of FIGURE 2, wherein the direction line 16 of ram movement is vertical. As noted earlier, however, the upper frame structure 38 is mounted on the frame base 32 for rotation to any other desired angular position. In this regard, for example, it is significant to note that in the position of the frame structure illustrated in FIGURE 2, gravity aids the travel of the upper forming ram 14 through its forming stroke and impedes the travel of the lower forming ram through its forming stroke. This creates an unbalanced force condition on the forming rams which may be undesirable in some formingapplications. In these applications, the effect of gravity on the forming rams may be equalized by rotation of the upper frame structure 38 to its position of FIGURE 6, wherein the direction line 16 of ram movement is horizontal.

At this point, several unique and highly advantageous features of the forming machine are obvious. One of these important features resides in the three fold function of the toggles 72. Thus, these toggles serve, first, to transform the relatively small and generally constant output forces of the ram actuators 46a, 4612 into large retraction forces on the forming rams 14 which increase sharply in magnitude with the increase in working fluid pressure Within the expansible pressure chamber 62 occasioned by approach of the rams to their fully retracted positions of FIGURE 4. Secondly, the toggles effect precisely synchronized release of the forming rams for impulsion through their forming strokes under the force of the compressed working fluid in the pressure chamber in response to movement of the toggle knee joint 78 to their dead center positions. Thirdly, the toggles are effective to precisely synchronize movement of the rams through their 14 forming strokes in such a way that the ram velocities are precisely equalized upon arrival of the rams at their forming positions of FIGURE 3. As noted earlier, the ram masses are also equalized. Accordingly, the forming rams arrive at their forming positions of FIGURE 3 with precisely matched kinetic energies. The rams, of course, are effectively isolated from the machine frame during their forming strokes. As a consequence, the total impact energy of the forming rams is absorbed totally by the workpiece and the rams themselves, and the rams are arrested at the conclusion of their forming strokes without any appreciable shock loading of the machine frame, components mounted on the frame, or the supporting floor through which the frame is attached. It is unnecessary, therefore, to mount the machine on a massive foundation, as required in many impact forming machines. The elimination of shock loading of the machine frame also results in longer service life, greater reliability of operation, and overall improved operating characteristics of the machine, and permits a relatively light weight low cost machine construction. These factors, in turn, permit the ram structure to be rotatably mounted on the machine frame, which is advantageous for the reasons discussed earlier.

The toggles 72 serve an additional, highly important safety function. Thus, since these toggles constrain the forming rams 14 to synchronized movement through their forming strokes, retardation or arresting of either ram in its foming stroke, due to jamming or binding of the ram in its cylinder 58, will result either in corresponding retardation or arresting of the other ram or in freeing of the faulty ram. As a consequence, it is impossible for impact of the rams to occur under conditions other than those which yield accurately matched kinetic energies of the ram. As noted earlier, this is in distinct contrast to the existing forming machines wherein the forming rams are capable of independent movement. In these existing machines, then, either ram may continue in its high velocity forming movement even though the other ram should stall. Impact of the rams under these conditions, of course, would at least cause severe damage to the forming machine and might very likely cause disintegration of the machine, thus creating a serious safety hazard to the operating personnel. From what was said above, it is obvious that this potential safety hazard inherent in the existing forming machines is eliminated in the present forming machine.

It will be recalled that the toggle wrist pins 84 are capable of limited axial floating movement relative to the forming rams 14 and that the forward movement of these wrist pins, at impact, is gradually arrested by the wrist pin shock absorbing means (FIGURE 3a or FIGURE 3b) embodied in the forming rams. These shock absorbing means reduce the shock loading on the wrist pins at impact sufficiently to prevent bending or other damage to the wrist pins.

It will be recalled that the successive forming cycles of the forming machine under discussion are effected by driving the toggles 72 first in one direction and then in the opposite direction through their dead center positions. This unique toggle action of the machine adapts the latter for fast cycling operation and, therefore, for installation in a manufacturing production line. Thus, the machine may be operated as rapidly as the workpieces 30 can be fed to and removed from the machine. In this regard, it is obvious that the forming machine may be automated by providing a suitable workpiece feeding or indexing device for automatically feeding unformed workpieces to the forming dies of the machine in timed relation to the cycling operation of the machine.

It is evident at this point that the present forming machine may be used for various forming operations involving a Wide range of forming ram impact energies. As noted earlier, however, the machine is particularly designed for high energy rate forming applications involving extremely high ram impact energies sufficient to 15 cause plastic behavior of relatively hard work materials, such as alloy steels, and resulting plastic flow of these work materials into conforming relation with the forming die cavity. These high energy rate forming applications require compressed working fluid pressures on the order of 10,000 p.s.i. In order to attain these high working fluid pressures, it may be necessary to charge the expansible pressure chambers 62 of the machine with working fluid, from the Working fluid source 154, under an initial pressure which will yield the desired final high working fluid pressure when the working fluid in the pressure chambers is compressed by retraction of the forming rams 14. It is well known, of course, that optimum high energy rate forming of a workpiece requires precise controlling of the impact energy delivered to the workpiece. Such precise energy control in the present high energy rate forming machine may be obtained by appropriate selection of the ram masses, regulation of the initial working fluid pressure in the expansible pressure chambers 62, and/ or appropriate selection of the various other parameters which determine the impact energy delivered to the workpiece by the forming rams 14. Precise matching of the kinetic energies of the forming rams 14 at impact is particularly essential in high energy rate forming applications, not only to minimize or eliminate shock loading of the machine frame and its supporting floor, but also to assure application of precisely controlled impact forming energy to the workpiece. It is for this reason that the illustrated forming machine is provided with the conduit 150 for communicating the expansible pressure chambers 62 of the machine. This communication between the pressure chambers achieves precise equalization of the working fluid pressures in the chambers and, thereby, precise matching of the velocities, and hence kinetic energies, of the forming rams at impact. In this regard, it will be understood that the fluid conduit 150 is provided with a sufficiently large bore to assure free communication between the pressure chambers and, thereby, precise equalization of the chamber pressures throughout the entire working or forming strokes of the forming rams. It will be further understood that the forming rams are precisely matched to have, not only equal masses, as discussed earlier, but also equal effective areas exposed to the working fluid pressure in the pressure chambers.

Reference is now made to FIGURES 8 through 17 illustrating a modified and presently preferred embodiment of the present forming machine. The modified forming machine 200 is basically similar to the forming machine described above in that the modified machine embodies a frame 202 mounting a pair of forming rams 204 for movement along a common direction line 206. Associated with these forming rams are retraction means 208 for driving the rams from their extended forming positions of FIGURES 8, 9, 12 and 17 to their retracted positions of FIGURE 16 and ram driving means 210 for driving or impelling the rams from the retracted positions to their forming positions. As in the previous form of the invention, the ram retraction means 208 embody force multiplying or amplifying toggle linkage means 212 for retracting the forming rams 204 against Working fluid pressure in such a way that the retraction forces active on the rams increases sharply with the increase in working fluid pressure occasioned by approach of the rams to their fully retracted positions, for

affecting precisely synchronized release of the forming rams for impulsion through their forming strokes by the compressed working fluid, and for effecting precisely synchronized movement of the forming rams through their forming strokes, thus to achieve precise matching or balancing of the kinetic energies of the rams at impact. This precise matching of the ram energies at impact minimizes or eliminates high rate impact loading of the machine frame and its supporting floor and accommodates a relatively light weight low cost machine con- 16 struction, thus eliminating the necessity of a supporting foundation for the machine and permitting rotatable mounting of the forming ram structure, as in the earlier embodiment of the invention.

Referring nOW in greater detail to the modified forming machine 200, the machine frame 202 includes a supporting base 214 having upstanding plate like arms 216, and an upper frame structure 218 which is disposed between and rotatably supported on the upper ends of the base arms 216. The upper frame structure 218 includes a pair of spaced, generally rectangular frame plates 220 having arm like formations 222 projecting laterally from their longitudinal edges, intermediate the ends of the plates. Disposed between and welded or otherwise rigidly joined to the frame plates 220, adjacent the ends of these plates, are a pair of frame blocks 224. The longitudinal axes of the frame plates 220 parallel the direction line 206 of movement of the forming rams 204. The frame blocks 224 are centered on and are disposed in planes normal to this direction line. Frame blocks 224 are joined by a pair of guide rods 226 having reduced, shouldered ends which extend through openings in corresponding diagonally opposite corners of the blocks. Nuts 228 are threaded on the ends of these guide rods to firmly secure the rods to the frame blocks 224. Guide rods 226 parallel the direction line 206 of forming ram movement.

Forming rams 204 comprise coaxial cylinders 230 having inner confronting working ends 232 closed by end Walls 234. The opposite, outer ends of the ram cylinders 230 are open. Bolted or otherwise firmly attached to the inner end wall 234 of each ram cylinder 230 is a slide 236. The outer end of each ram cylinder extends through a central opening in a second slide 238 which is welded or otherwise rigidly joined to the respective cylinder. Slides 236 and 238 have openings in diagonally opposite corners thereof slidably receiving the guide rods 226. It is evident at this point, therefore, that the guide rods 226 and the slides 236, 238 slidably support the ram cylinders 230 on the upper frame structure 218 for movement along the direction line 206.

Ram retraction means 208 comprise, in addition to the toggle linkage means 212, a pair of hydraulic or pneumatic actuators 240 including coaxial cylinders 242, the common axis of which extends normal to the direction line 206 of the forming ram movement. The inner ends of the actuator cylinders 242 are located between the frame plate arm formations 222 and have external rectangular shoulders 244 which seat flush against and are welded or otherwise rigidly joined to the inner surfaces of these formations. Slidable within each actuator cylinder 242 is a piston having a rod 246 which extends from the inner end of the respective cylinder. A bearing fork 248 is rigidly joined to the outer end of each actuator piston rod 246. Each bearing fork 248 has spaced, inwardly directed fork arms 250.

Rigidly mounted on the inner surfaces of the frame plates 220, just inwardly of each ram actuator 240, are a pair of guides 252. These guides have aligned guide slots or tracks 254 disposed in a common plane normal to the frame plates 220 and containing the axis of the actuator cylinders 242. The longitudinal sides of each actuator bearing fork 248 fit slidably within the adjacent guide slots 254. Accordingly, the bearing forks slide back and forth along and are restrained against rotation about the axis of the actuator cylinders 242 by the guides 252 during extension and retraction of the actuator piston rods 246.

The toggle linkage means 212 of the forming machine under discussion comprise a pair of toggles 256. Each toggle 256 includes a pair of toggle bars 258, 260 which are pivotally joined at their inner ends by a knee joint 262. The toggle knee joints 262 are disposed between the arms 250 of the actuator bearing forks 248, respectively, and include knee shafts 264 which are engaged by recessed end faces of the adjacent fork arms 250, in the manner shown best in FIGURE 15. Referring to FIG- URE 14, it will be observed that the bearing fork guides 252 are longitudinally grooved to receive the projecting ends of the toggle knee shafts 264. The opposite or outer ends of the toggle bars 258, 260 are pivotally attached to a pair of thrust plates 266 which are slidably supported on the guide rods 226. These thrust plates are located between the slides 236, 238 for the ram cylinders 230, respectively. Each thrust plate has a central opening slidably receiving the adjacent ram cylinder. Each ram cylinder has an external, inwardly facing annular shoulder 268 against which the adjacent thrust plate 266 is adapted to seat to transmit an outward retraction force on the respective cylinder.

At this point, it is evident that inward extension of the actuator piston rods 246 is eifective to drive the toggle knee joints 262 inwardly toward their positions of FIG- URE 16, wherein the knee joints are located slightly beyond their dead center positions. The knee joint positions illustrated in FIGURE 16 are hereinafter referred to as their over center positions. It is significant to note here that the inner ram cylinder slides 236 and the thrust plates 2-66 are notched to accommodate movement of the toggle bars 258, 260 to their over center positions of FIGURE 16. It is obvious that this inward movement of the toggle knee joints 262 to their over center positions is effective to initially drive the thrust plates 266 outwardly into seating engagement with the ram cylinder thrust shoulders 268 and thereafter to drive the thrust plates and ram cylinders outwardly in unison to the retracted positions of the cylinders illustrated in FIGURE 16. As in the previous form of the invention, the retraction forces exerted on the ram cylinders 230 by the toggles 256 increase sharply as the toggle knee joints 262 approach their dead center positions and the ram cylinders 230 approach their fully retracted positions. The toggles 256 are also effective, obviously, to synchronize movement of the ram cylinders 230 from their retracted positions to their forming positions of FIG- URES 9 and 17.

The forming ram driving or impulsion means 210 of the forming machine 200 comprise pistons 270 which are rigidly joined to the fixed frame blocks 224 and fit slidably within the ram cylinders 230. The ram cylinders and pistons cooperatively define expansible pressure chambers 272 containing a working fluid, such as any one of those fluids mentioned earlier. As in the previous form of the invention, the working fluid in the pressure chambers 272 is compressed by outward retraction of the forming ram cylinders 230.

It is now evident that the forming rams 204 comprise the ram cylinders 230 and the ram cylinder slides 236, 238. During operation of the forming machine, the work forming dies 274 are mounted on the inner confronting faces of the inner cylinder slides 236. As in the previous form of the invention, these dies are movable into percussive work forming relation about a workpiece 276 by inward impulsion of the forming rams 204 through their forming strokes under the force of the compressed working fluid in the expansible pressure chambers 272. During these inward forming strokes of the forming rams, the ram thrust plates 266 acquire substantial momentum or kinetic energy which tends to cause continued forward or inward movement of these plates after impact of the forming dies with the workpiece. For this reason, the forming machine is equipped with shock absorbing means 278 for arresting the thrust plates 266 with minimal shock loading. Various forms of shock absorbing means may be employed for this purpose. The illustrated shock absorbing means comprise pistons 280 which are rigidly secured to the inner forming ram slides 236 and fit slidably within piston bores 282 in the forming ram thrust plates 266. These piston bores communicate with their adjacent forming ram pressure chambers 272 through restricted bleed passages 284 in the respective forming rams and additional restricted bleed passages in the pistons 280. It is evident, therefore, that during operation of the forming machine, working fluid will bleed from the pressure chambers 272 into the piston bores 282 and will impede forward or inward movement of the thrust plates 266 relative to the pistons 280, thus to gradually arrest the thrust plates following impact of the forming dies 274 with the workpiece 276.

The forming machine under discussion is equipped with means 286 for ejecting the formed workpiece from its containing forming die cavity. Ejecting means 286 comprise a pair of cylinders 288 which are rigidly secured to the outer surfaces of the fixed frame blocks 224 in coaxial alignment with the forming ram cylinders 230 and pistons 270. Slidable in each ejector cylinder 288 is a piston 290 having a rod 292 which extends through theadjacent frame block 224 and piston 270 into a bearing sleeve 294, which extends through and is fixed to the inner end of the adjacent forming ram 204 and slides within a bore in the adjacent ram piston 270. The ejector rods 292 and the bearing sleeves 294 are sealed, as shown, to prevent the fluid leakage. The ejector rods 292 are axially movable between their retracted positions of FIGURE 12, wherein the inner ends of the rods are retracted into the bearing sleeves 294, and their extended positions of FIGURE 16, wherein the inner ends of the rods project beyond the inner ends of the forming rams 204 and through the forming dies 274. At the conclusion of .each forming cycle, the ejector rod associated with the forming die containing the finished work part is extended to eject the part.

It 'will be recalled that the toggle knee joints 262 are adapted to be driven, by the ram actuators 240, from their limiting positions of FIGURE 12 to their over center positions of FIGURE 16 to aflect retraction of the forming rams 204 against the working fluid pressure within the pressure chambers 272. Movement of the toggles beyond these over center positions is limited by engagement of the toggle bars 258, 260 with the bottom walls of the toggle bar clearance slots or notches in the inner forming ram slides 236. It is obvious that the toggles 256, when in these over center positions, are effective to retain the forming rams 204 in their retracted positions of FIGURE 16 against the force of the compressed working fluid in the pressure chambers 272. Means 296 are provided for driving the toggles 256 from their over center positions back through and slightly beyond their dead center positions, thus to release the forming rams 204 for impulsion through their forming strokes under the force of the compressed working fluid. The illustrated toggle release means 296 comprise a pair of toggle release levers 298 pivotally mounted on the machine frame 202. These toggle release levers have tapered camming arms 300 which are engageable with projecting lugs 302 rigid on the toggle bars 258. When the toggles 256 occupy their over center positions of FIGURE 16, the toggle bar lugs 302 seat against the arms 300 of the toggle release levers 298, as shown. It is evident at this point that upward rotation of the toggle release levers 298, as viewed in FIGURE 16, is effective to urge the tapered lever arms 300 against the toggle bar lugs 302 and thereby drive the toggles 256 outwardly from their illustrated over center positions through their dead center positions, thus to release the forming rams 204 for im ulsion through their forming strokes. Such upward rotation of the toggle release levers 298 is effected by lever actuating means 304 on the machine frame. These lever actuating means may comprise solenoids or fluid pressure actuators, for example. Preferably, means are provided for preventing downward rotation of the levers 298 beyond the position of FIGURE 16, whereby abutment of the toggle bar lugs 302 against the lever arms 300 aids in preventing movement of the toggles 256 beyond their over center positions. Attention is directed to the fact that the e 19 toggle bars 258 are longitudinally slotted to clear the toggle release levers 298 and their actuating means 304 during movement of the toggles from their over center positions of FIGURE 16 to their limiting positions of FIGURE 12.

Reference is now made to FIGURE 17 which illustrates the hydraulic system of the modified forming machine. Since this hydraulic system is believed to be self evident from the drawings, it will be described only in general terms. Suffice it to say that the hydraulic system includes a first hydraulic circuit 306 for effecting simultaneous extension and retraction of the piston rods 246 of the forming ram actuators 240, hydraulic circuits 308 and 310 for selectively extending and retracting the work piece ejector rods 292, and a hydraulic circuit 312 for operating the toggle release lever actuating means 304, which are shown in FIGURE 17 to comprise hydraulic actuators. Reference numeral 314 in FIGURE 17 designates a working fluid supply system for charging the expansible pressure chambers 272 of the forming machine with working fluid. The working fluid supply system includes a pressurized source 316 of the working fluid and solenoid valves 318 for selectively communicating the fluid supply 316 to the pressure chambers 272 through fluid lines 320 which extend axially through the stationary forming ram pistons 270. An adjustable fluid pressure regulator 322 is placed between the fluid supply 316 and the pressure chambers, as shown, to permit selective regulation of the pressure of the working fluid delivered to the pressure chambers, thus to permit regulation of the initial working fluid pressure in the chambers and hence the final pressure to which the working fluid is compressed by retraction of the forming rams 204. The pressure chambers 272 freely communicate through a relatively large fluid line 324, as in the previous form of the invention, thus to equalize the working fluid pressures in the two pressure chambers, for the reasons mentioned earlier.

The operation of the modified forming machine is believed to be obvious from the foregoing description. Thus, a forming cycle of the machine is initiated by pressurizing the ram actuators 240 in directions to drive the toggles 256 to their over center positions of FIGURE 16 and thereby retract the forming rams 204 against the pressure of the working fluid within the expansible pressure chambers 272. This retraction of the forming rams is eifective to compress the working fluid in the pressure chambers to the high pressure level required for forming operation of the machine. Movement of the toggles 256 to their over center positions of FIGURE 16 effectively latches the forming rams 204 in their retracted positions against the force of the compressed working fluid. At this point, a workpiece or billet 276 is placed in the cavity of the lower forming die 274. The ram actuators 240 are then pressurized in directions to retract their piston rods 246 and their bearing forks 248, thus to free the toggles 256 for unrestricted outward movement and thereby condition the machine for subsequent inward forming strokes of the forming rams 240.

The forming strokes of the forming rams 204 are initiated by operating the actuating means 304 for the toggle release levers 298, thus to drive these levers upwardly in FIGURE 16 and thereby drive the toggles 256 outwardly from their over center positions of the latter figure through and slightly beyond their dead center positions. The forming rams 204 are thereby simultaneously released for inward impulsion through their forming strokes by the compressed working fluid in the expansible pressure chambers 272. At the conclusion of these forming strokes, the forming dies 274 enter into percussive forming relation about the workpiece 276, thus to deform the workpiece into conforming relation with the forming die cavity, in the manner explained earlier. The forming ram actuators 240 are then again pressurized to retract the rams, after which the formed workpiece is ejected from its containing forming die by pressurizing the corresponding 2.0 ejector cylinder 288 to extend the corresponding ejector rod 292, as shown in FIGURE 16.

It is now obvious that the modified forming machine possesses the same inherent unique features and advantages as the forming machine described earlier. Accordingly, these features and advantages need not be repeated. It should be noted, however, that the modified forming machine of FIGURES 8 through 17 is superior to the earlier forming machine of FIGURES 1 through 7 for the reason that the forming rams 204 may be latched in their retracted positions, thus to facilitate placement of the unformed workpiece end and removal of the formed Workpiece from the machine. It will be understood, of course, that the modified forming machine, like the earlier forming machine, is susceptible of a variety of forming applications but is particularly designed for high energy rate forming applications.

It is obvious, therefore, that the invention herein described and illustrated is fully capable of attaining the several objects and advantages preliminarily set forth.

Although specific embodiments of the present invention have been illustrated and described herein, it will be understood that the same are merely exemplary of presently preferred embodiments capable of attaining the objects and advantages hereinbefore mentioned, and that the invention is not limited thereto; variations will be readily apparent to those versed in the art, and the invention is entitled to the broadest interpretation within the terms of the appended claims.

I claim:

1. An impact forming machine comprising:

a frame,

a pair of forming rams having confronting working ends,

means mounting said rams on said frame for movement along a common direction line relative to said frame between remote retracted positions and proximate forming positions, toggle linkage means positively connecting said rams for effecting precisely synchronized movement of said rams in unison between said positions comprising a toggle including a pair of toggle bars having their adjacent ends pivotally connected by a knee joint and their remote ends pivotally connected to said rams, respectively, in such manner that said knee joint undergoes movement along a second direction line transverse to said first mentioned direction line during said synchronized ram movement between said positions, and coacting guide means on said frame and toggle for constraining said knee joint to movement along said second direction line,

said knee joint having a dead center position along said second direction line and said rams being movable to said retracted positions thereof in response to movement of said knee joint to said dead center position,

power means operative between said frame and toggle for driving said knee joint to said dead center position, thereby to drive said rams to their retracted positions, and thereafter driving said knee joint from said dead center position and releasing said toggle for unrestricted movement of said knee joint along said second direction line, thereby to releasesaid rams for movement to said forming positions thereof, and

means for driving said rams to their forming positions following said release thereof.

2. An impact forming machine comprising:

afra-me,

a pair of forming rams having confronting working ends,

means mounting said rams on said frame for movement along a common direction line relative to said frame between remote retracted positions and proximate forming positions,

mechanical linkage means positively connecting said rams for effecting precisely synchronized movement of said rams in unison between said positions,

yieldable ram driving means for impelling said rams to said forming positions thereof, and

power means on said frame for driving said rams to their retracted positions against the force of said ram driving means and then releasing said rams for synchronized movement to their forming positions under the force of said driving means and the synchronizing action of said linkage means.

3. An impact forming machine according to claim 2 wherein:

said linkage means are movable from a first position to a second position to drive said rams from their forming positions to their retracted positions and said linkage means are movable from said second position to another position to release said rams for movement from their retracted positions to their forming positions, and

said linkage means are operatively connected between said power means and said rams in such manner that said power means are effective to drive said linkage means from said first position to said second position and thereafter release said linkage means for movement to said other position thereof.

4. An impact forming machine comprising:

aframe,

a pair of forming rams having confronting working ends,

means mounting said rams on said frame for movement along a common direction line relative to said frame between remote retracted positions and proximate forming positions,

mechanical linkage means positively connecting said rams for effecting precisely synchronized movement of said rams in unison between said positions,

yieldable drive means for impelling said forming rams to their forming positions,

said linkage means comprising a toggle including a pair of toggle bars having their adjacent ends pivotally connected by a knee joint and their remote ends pivotally connected to said rams, respectively, in such manner that said knee joint undergoes movement along a second direction line transverse to said first mentioned direction line during said synchronized ram movement between said positions, and coacting guide means on said frame and toggle for constraining said knee joint to movement along said second direction line,

said knee joint being movable through a dead center position along said second direction line and said rams being movable to their retracted positions in response to movement of said knee joint to said dead center position,

power means operative between said frame and said toggle for driving said knee joint to said dead center position, thereby to drive said rams to their retracted positions against the force of said ram driving means and thereafter driving said knee joint from said dead center position and releasing said toggle for unrestricted movement of said knee joint along said second direction line, thereby to release said rams for movement to their forming positions under the force of said ram driving means.

5. An impact forming machine according to claim 4 wherein:

tially drive said rams from their forming positions to their retracted positions and then release said rams for movement from their retracted positions to their forming positions, and

22 said power means are effective to drive said knee joint from said first limiting position to a position slightly beyond said dead center position and then release said toggle for unrestricted movement of said knee joint to said second limiting position. 6. An impact forming machine according to claim 5 including:

additional power means operative between said frame and toggle for driving said knee joint from said second limiting position to a position slightly beyond said dead center position and then releasing said toggle for unrestrained movement of said knee joint to said first limiting position, and

means for operating said power means alternately.

7. An impact forming machine comprising:

a frame,

a pair of forming rams having confronting working ends,

means mounting said rams on said frame for movement along a common direction line relative to said frame between remote retracted positions and proximate forming positions,

mechanical linkage means positively connecting said rams for effecting precisely synchronized movement of said rams in unison between said positions,

yieldable drive means for impelling said rams to their forming positions,

said linkage means comprising a toggle including a pair of toggle bars having their adjacent ends pivotally connected by a knee joint and their remote ends pivotally connected to said rams, respectively, in such manner that said knee joint undergoes movement along a second direction line transverse to said first mentioned direction line during said synchronized ram movement between said positions, and coacting guide means on said frame and toggle for constraining said knee joint to movement along sai second direction line,

said knee joint occupying a limiting position along said second direction line when said rams occupy their forming positions and said knee joint being movable along said second direction line from said limiting position through a dead center position to a slightly over center position to drive said rams to their retracted positions,

power means operative between said frame and toggle for driving said knee joint from said limiting position to said over center position, thereby to drive said rams to their retracted positions against the force of said ram driving means,

means for releasably retaining said knee joint in said over center position, thereby to releasably retain said rams in their retracted positions against the force of said ram driving means, and

toggle release means operative between said frame and toggle for driving said knee joint from said over center position through said dead center position and then releasing said toggle for unrestrained movement of said knee joint to said limiting position, thereby to release said rams for impulsion to their forming positions under the force of said said ram driving means.

8. An impact forming machine comprising:

a frame,

a pair of forming rams having confronting working ends,

means mounting said rams on said frame for movement along a common direction line relative to said frame between remote retracted positions and proximate forming positions,

toggle linkage means positively connecting said rams for effecting precisely synchronized movement of said rams in unison between said positions,

means cooperating with said rams to define expansible pressure chambers containing compressible working pressure of the working fluid in said pressure chambers.

9. An impact forming machine comprising:

a frame,

a forming ram mounted on said frame for movement between a retracted position and its forming position, a toggle operatively connected between said frame and ram and including a knee joint which is movable position to a dead center position from said forming position to said against the force of said ram drivunder the force of said ram driving means.

10. An impact forming machine according to claim 9 wherein:

said knee joint is movable from said limiting position through said dead center position to a second limiting position to effect initial driving of said ram to its retracted position and subsequent release of said ram for impulsion to its forming position, and

and slightly beyond said dead center position and then release said toggle for unrestrained movement of said knee joint to said second limiting position.

11. An impact forming machine according to claim 9 wherein:

said knee joint is movable from said limiting position through said dead center position to an over center position slightly beyond said dead center position and from said over center position back through said dead center position to said limiting position to initially drive said ram to its retracted position and thereafter release said ram for impulsion to its forming position,

said power means is effective to drive said knee joint from said limiting position to said over center position,

means for releasably retaining said knee joint in its over center position, thereby to retain said ram in its retracted position against the force of said ram driving means, and

toggle release means operative between said frame and toggle for driving said knee joint from said over center position through and slightly beyond said dead center position and then releasing said toggle for said ram driving means.

12. An impact forming machine according to claim 9 wherein:

said toggle includes a toggle bar and means including a wrist pin extending transversely through said ram for pivotally connecting said toggle bar to said ram,

said wrist pin being capable of limited floating movement axially of said ram, and

shock absorbing means operative between said ram and wrist pin for yieldably resisting movement of said Wrist pin axially of said ram in the direction of said forming position of the ram.

for limited axial movement on said ram, and means the forming 14. An impact a frame,

position of said ram.

forming machine comprising:

a pair of forming rams having working ends, means mounting said rams on said frame for relative ram driving means for impelling said rams from their retracted positions to their forming positions,

tion, thereby to release said rams for impulsion to their forming positions.

16. An impact forming machine comprising:

a frame including a lower base portion and an upper frame structure forming positions, means for driving said rams from their forming positions to their retracted positions, 

